indication

Used for protein synthesis including the formation of SAMe, L-homocysteine, L-cysteine, taurine, and sulfate.

pharmacology

L-Methionine is a principle supplier of sulfur which prevents disorders of the hair, skin and nails; helps lower cholesterol levels by increasing the liver's production of lecithin; reduces liver fat and protects the kidneys; a natural chelating agent for heavy metals; regulates the formation of ammonia and creates ammonia-free urine which reduces bladder irritation; influences hair follicles and promotes hair growth. L-methionine may protect against the toxic effects of hepatotoxins, such as acetaminophen. Methionine may have antioxidant activity.

mechanism of action

The mechanism of the possible anti-hepatotoxic activity of L-methionine is not entirely clear. It is thought that metabolism of high doses of acetaminophen in the liver lead to decreased levels of hepatic glutathione and increased oxidative stress. L-methionine is a precursor to L-cysteine. L-cysteine itself may have antioxidant activity. L-cysteine is also a precursor to the antioxidant glutathione. Antioxidant activity of L-methionine and metabolites of L-methionine appear to account for its possible anti-hepatotoxic activity. Recent research suggests that methionine itself has free-radical scavenging activity by virtue of its sulfur, as well as its chelating ability.

toxicity

Doses of L-methionine of up to 250 mg daily are generally well tolerated. Higher doses may cause nausea, vomiting and headache. Healthy adults taking 8 grams of L-methionine daily for four days were found to have reduced serum folate levels and leucocytosis. Healthy adults taking 13.9 grams of L-methionine daily for five days were found to have changes in serum pH and potassium and increased urinary calcium excretion. Schizophrenic patients given 10 to 20 grams of L-methionine daily for two weeks developed functional psychoses. Single doses of 8 grams precipitated encephalopathy in patients with cirrhosis.

biotransformation

Hepatic

absorption

Absorbed from the lumen of the small intestine into the enterocytes by an active transport process.